Giải phương trình sau :
\(\left(1-\frac{1}{5}\right)\left(1-\frac{1}{21}\right)\left(1-\frac{1}{28}\right)\left(1-\frac{1}{36}\right)\left(1-\frac{1}{45}\right)\left(1-\frac{1}{55}\right)\left(5x+10\right)+2=2x+5\)
Giải phương trình sau :
\(\left(1-\frac{1}{5}\right)\left(1-\frac{1}{21}\right)\left(1-\frac{1}{28}\right)\left(1-\frac{1}{36}\right)\left(1-\frac{1}{45}\right)\left(1-\frac{1}{55}\right)\left(5x-10\right)+2=2x+5\)
\(E=\left(\frac{1}{3}-1\right)\left(\frac{1}{6}-1\right)\left(\frac{1}{10}-1\right)\left(\frac{1}{15}-1\right)\left(\frac{1}{21}-1\right)\left(\frac{1}{28}-1\right)\left(\frac{1}{36}-1\right)\)
\(=\frac{-2}{3}\cdot\frac{-5}{6}\cdot\frac{-9}{10}\cdot\cdot\cdot\cdot\frac{-35}{36}\)
\(=\frac{-4}{6}\cdot\frac{-10}{12}\cdot\frac{-18}{20}\cdot\cdot\cdot\cdot\frac{-70}{72}\)
\(=\frac{-1.4}{2.3}\cdot\frac{-2.5}{3.4}\cdot\frac{-3.6}{4.5}\cdot\cdot\cdot\cdot\frac{-7.10}{8.9}\)
\(=\frac{\left(-1\right).\left(-2\right).\left(-3\right)...\left(-7\right)}{2.3.4....8}\cdot\frac{4.5.6....10}{3.4.5....9}\)
\(=\frac{\left(-1\right).2.3...7}{2.3.4....8}\cdot\frac{10}{3}\)
\(=\frac{-1}{8}\cdot\frac{10}{3}=\frac{-5}{12}\)
Tính:
\(M=\left(1-\frac{1}{3}\right)\left(1\frac{1}{6}\right)\left(1-\frac{1}{10}\right)\left(1-\frac{1}{15}\right)\left(1-\frac{1}{21}\right)\left(1-\frac{1}{28}\right)\left(1-\frac{1}{36}\right)\)
Tính Tổng :
\(M=\left(1-\frac{1}{3}\right)\left(1-\frac{1}{6}\right)\left(1-\frac{1}{10}\right)\left(1-\frac{1}{15}\right)\left(1-\frac{1}{21}\right)\left(1-\frac{1}{28}\right)\left(1-\frac{1}{36}\right)\)
Mong mọi người giúp đỡ
Bài 1 : Tính
\(A=\left(\frac{1}{3}-1\right).\left(\frac{1}{6}-1\right).\left(\frac{1}{10}-1\right).\left(\frac{1}{15}-1\right).\left(\frac{1}{21}-1\right).\left(\frac{1}{28}-1\right).\left(\frac{1}{36}-1\right)\)
HÃY CỐ GẮNG GIÚP MÌNH NHA CÁC P !!!
A = ( 1/3 - 1).( 1/6 - 1).( 1/10 - 1).( 1/15 - 1).( 1/21 - 1).( 1/28 - 1).( 1/36 - 1)
A = -2/3 . ( -5/6) . ( -9/10) . ( -14/15) . ( -20/21) . ( -27/28) . ( -35/36)
Do tích A có lẻ thừa số, mỗi thừa số đều mang dấu âm nên A mang dấu âm
A = -[ 2/3 . 5/6 . 9/10 . 14/15 . 20/21 . 27/28 . 35/36]
Đặt B = 2/3 . 5/6 . 9/10 . 14/15 . 20/21 . 27/28 . 35/36
B = 4/6 . 10/12 . 18/20 . 28/30 . 40/42 . 54/56 . 70/72
B = 1.4/2.3 . 2.5/3.4 . 3.6/4.5 . 4.7/5.6 . 5.8/6.7 . 6.9/7.8 . 7.10/8.9
B = 1.2.3.4.5.6.7/3.4.5.6.7.8.9 . 4.5.6.7.8.9.10/2.3.4.5.6.7.8
B = 2/8.9 . 9.10/2.3
B = 5/12
A = -5/12
cÓ ĐÚNG KO VẬY P NẾU ĐÚNG THÌ CHO MIK THANK Y NHA
\(\left(1-\frac{1}{21}\right).\left(1-\frac{1}{28}\right).\left(1-\frac{1}{36}\right).........\left(1-\frac{1}{1026}\right)\)
khó z mik ko giai duoc k cho mik ik mik kb cho nha
Đặt \(A=\left(1-\frac{1}{21}\right).\left(1-\frac{1}{28}\right).\left(1-\frac{1}{36}\right).....\left(1-\frac{1}{1026}\right)\)
\(A=\frac{20}{21}.\frac{27}{28}.\frac{35}{36}....\frac{1025}{1026}=\frac{40}{42}.\frac{54}{56}.\frac{70}{72}....\frac{2050}{2052}\)
\(A=\frac{40.54.70.......2050}{42.56.72.....2052}=\frac{5.8.6.9.7.10.....a.\left(a+3\right)}{6.7.7.8.8.9....b.\left(b+1\right)}=\frac{\left(5.6.7...a\right).\left[8.9.10....\left(a+3\right)\right]}{\left(6.7.8.9...b\right).\left[7.8.9....\left(b+1\right)\right]}\)
Tôi chỉ làm đến đây thôi , đề bài sai ở phân số cuối nhé , nếu sửa đề thì thay các số vào a và b nhé
Tớ nghĩ đề bài hơi SAI
Theo tớ là phải:
= 20/21 . 27/28 . 35/36 ..... 1325/1326
= 40/42 . 54/56 . 70/72 ..... 2650/2652
= 5.8/6.7 . 6.9/7.8 . 7.10/8.9 ..... 50.53/51.52
= 5.53/7.51
=265/357
Tính các tích sau:
a)\(A=\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.....\frac{9999}{10000}\)
b)\(B=\left(1-\frac{1}{21}\right).\left(1-\frac{1}{28}\right).\left(1-\frac{1}{36}\right)......\left(1-\frac{1}{1326}\right)\)
c)\(C=\left(1+\frac{1}{1.3}\right).\left(1+\frac{1}{2.4}\right).\left(1+\frac{1}{3.5}\right)....\left(1+\frac{1}{99.101}\right)\)
Tính các tích sau: A = \(\left(1-\frac{1}{21}\right)\left(1-\frac{1}{28}\right)\left(1-\frac{1}{36}\right)...\left(1-\frac{1}{1326}\right)\)
thong diep nho :
hay kỉ ko muốn
ai tích mình tích lại nha
tính các tích sau: \(A=\left(1-\frac{1}{21}\right)\times\left(1-\frac{1}{28}\right)\times\left(1-\frac{1}{36}\right)\times....\times\left(1-\frac{1}{1326}\right)\)
\(A=\frac{20}{21}\cdot\frac{27}{28}\cdot\frac{35}{36}\cdot...\cdot\frac{1325}{1326}\)
\(=\frac{40}{42}\cdot\frac{54}{56}\cdot\frac{70}{72}\cdot...\cdot\frac{2650}{2652}\)
\(=\frac{5\cdot8}{6\cdot7}\cdot\frac{6\cdot9}{7\cdot8}\cdot\frac{7\cdot10}{8\cdot9}\cdot...\cdot\frac{50\cdot53}{51\cdot52}\)
\(=\frac{5\cdot53}{7\cdot51}=\frac{265}{357}\)